diff --git a/core/includes/form.inc b/core/includes/form.inc
index 038cfca89ad..b5a13c55f0f 100644
--- a/core/includes/form.inc
+++ b/core/includes/form.inc
@@ -3361,7 +3361,7 @@ function form_process_tableselect($element) {
     $value = is_array($element['#value']) ? $element['#value'] : array();
   }
   else {
-    // Advanced selection behaviour make no sense for radios.
+    // Advanced selection behavior makes no sense for radios.
     $element['#js_select'] = FALSE;
   }
 
diff --git a/core/lib/Drupal/Core/Utility/CacheArray.php b/core/lib/Drupal/Core/Utility/CacheArray.php
index b730db2b7f0..bba2bc4e252 100644
--- a/core/lib/Drupal/Core/Utility/CacheArray.php
+++ b/core/lib/Drupal/Core/Utility/CacheArray.php
@@ -59,7 +59,7 @@ use ArrayAccess;
  * means that assigning an offset via arrayAccess will only apply while the
  * object is in scope and will not be written back to the persistent cache.
  * This follows a similar pattern to static vs. persistent caching in
- * procedural code. Extending classes may wish to alter this behaviour, for
+ * procedural code. Extending classes may wish to alter this behavior, for
  * example by overriding offsetSet() and adding an automatic call to persist().
  *
  * @see SchemaCache
diff --git a/core/modules/filter/filter.module b/core/modules/filter/filter.module
index 74c18234ff9..45f5170ce74 100644
--- a/core/modules/filter/filter.module
+++ b/core/modules/filter/filter.module
@@ -1111,7 +1111,7 @@ function filter_dom_serialize_escape_cdata_element($dom_document, $dom_element,
       $embed_suffix = "\n{$comment_start}--><!]]>{$comment_end}\n";
 
       // Prevent invalid cdata escaping as this would throw a DOM error.
-      // This is the same behaviour as found in libxml2.
+      // This is the same behavior as found in libxml2.
       // Related W3C standard: http://www.w3.org/TR/REC-xml/#dt-cdsection
       // Fix explanation: http://en.wikipedia.org/wiki/CDATA#Nesting
       $data = str_replace(']]>', ']]]]><![CDATA[>', $node->data);
diff --git a/core/modules/node/node.module b/core/modules/node/node.module
index a59a5c7efb3..bdd5051f085 100644
--- a/core/modules/node/node.module
+++ b/core/modules/node/node.module
@@ -3094,7 +3094,7 @@ function node_access($op, $node, $account = NULL) {
       return $result;
     }
     elseif (is_object($node) && $op == 'view' && $node->status) {
-      // If no modules implement hook_node_grants(), the default behaviour is to
+      // If no modules implement hook_node_grants(), the default behavior is to
       // allow all users to view published nodes, so reflect that here.
       $rights[$account->uid][$cid][$op] = TRUE;
       return TRUE;
diff --git a/core/modules/system/tests/form.test b/core/modules/system/tests/form.test
index 8bcce761120..b64fdd71823 100644
--- a/core/modules/system/tests/form.test
+++ b/core/modules/system/tests/form.test
@@ -813,12 +813,12 @@ class FormsElementsLabelsTestCase extends DrupalWebTestCase {
     $this->assertTrue(isset($elements[0]), t("Label 0 found radios."));
 
     // Exercise various defaults for checkboxes and modifications to ensure
-    // appropriate override and correct behaviour.
+    // appropriate override and correct behavior.
     $elements = $this->xpath('//input[@id="edit-form-checkbox-test"]/following-sibling::label[@for="edit-form-checkbox-test" and @class="option"]');
     $this->assertTrue(isset($elements[0]), t("Label follows field and label option class correct for a checkbox by default."));
 
     // Exercise various defaults for textboxes and modifications to ensure
-    // appropriate override and correct behaviour.
+    // appropriate override and correct behavior.
     $elements = $this->xpath('//label[@for="edit-form-textfield-test-title-and-required"]/child::abbr[@class="form-required"]/parent::*/following-sibling::input[@id="edit-form-textfield-test-title-and-required"]');
     $this->assertTrue(isset($elements[0]), t("Label precedes textfield, with required marker inside label."));
 
diff --git a/core/modules/user/user.test b/core/modules/user/user.test
index 42e237ac31f..bf0e486ad9b 100644
--- a/core/modules/user/user.test
+++ b/core/modules/user/user.test
@@ -1670,7 +1670,7 @@ class UserBlocksUnitTests extends DrupalWebTestCase {
 }
 
 /**
- * Test case to test user_save() behaviour.
+ * Tests user_save() behavior.
  */
 class UserSaveTestCase extends DrupalWebTestCase {
 
@@ -1759,7 +1759,7 @@ class UserCreateTestCase extends DrupalWebTestCase {
 }
 
 /**
- * Test case to test user_save() behaviour.
+ * Tests the user edit form.
  */
 class UserEditTestCase extends DrupalWebTestCase {